Process for thefjxation of vat dye-



Uted Stats 3,171,711 PROCESS FOR THE FHXATION ill VAT DYE- STUFFS N CELLULOSE FABRICS Frederick Richard Alsberg and Derrick William Hall Turner, Manchester, England, assignors to imperial Chemical industries Limited, London, England, a corporation of Great Britain No Drawing. 'lcd Feb. 25, 1963, Ser. No. 260,873 Claims priority, application Great Britain, Mar. 1, 1962, 8,639/62 8 Claims. (Cl. 8-74) This invention relates to a textile printing process and more particularly to an improved process for printing vat dyestuffs on cellulose fabrics such as cotton, linen and viscose.

Vat dyestulis are commonly printed on cellulose fabrics by a process which includes steaming the fabric for a period of about 5 to 20 minutes. Many printers, however, are now printing vat dyestuifs on cellulose fabrics by means of the so-called Flash-age process in which the fabric is steamed for a much shorter period, usually about 20 to 40 seconds. Such a process is obviously economic in time and in steam consumption.

Essentially the Flash-age process comprises printing on to the fabric a thickened printing paste containing a vat dyestufi dispersion and a thickener which coagulates on treatment with alkali, electrolyte or heat, and then padding the fabric with reducing agent and alkali and steaming for about 20 to 40 seconds without intermediate drying. Although such a process has been known for some time (see for example British patent specification No. 304,787) it has only recently become attractive to printers because suitable steaming equipment was not previously available.

In the Flash-age process it is necessary to use a reducing agent which will react very quickly and for this reason sodium dithionite (also known as sodium hydrosulphite) is commonly used as reducing agent. Dithionite is very unstable and becomes oxidised if the fabric, after padding, is exposed to the air for even a few seconds. The steaming equipment must therefore be positioned close to the padding mangle and this causes heating of the mangle bowls, which results in a progressive increase in temperature of the padding liquor and very rapid decomposition of the dithionite. Other reducing agents, for example acetaldehyde sulphoxylates (hydroxyalkylsulphinic acids) may be used in the Flash-age process. These products have better stability than dithionite, but are much more expensive. Sodium sulphoxylate formaldehyde has not hitherto been successfully used as re ducing agent in the Flash-age process because it does not react rapidly enough with vat dyestuffs.

It has long been known that catalysts can be used to increase the rate of reaction of sodium sulphoxylate formaldehyde with vat dyestufis and by this means steaming times of about 3 to 8 minutes have been achieved. We have now found means by which the rate of reaction of formaldehyde sulphoxylate with vat dyestuffs is increased sufiiciently to make possible the use of formaldehyde-sulphoxylate as reducing agent in the Flash-age process. By these means also improvements are efiected in the Flash-age process using any reducing agent for the vat dyestufi, particularly sodium dithionite and acetaldehyde sulphoxylate.

According to the invention we provide a process for the fixation of vat dyestulfs on cellulose fabrics which comprises steaming for not more than 2 minutes a cellulose fabric to which there has been applied a thickened vat dyestutf dispersion, an alkali, a reducing agent for the vat dyestulf and a reduction catalyst comprising a 7 3,171,711 Patented Mar. 2, 1%55 nickel salt or an organic or inorganic compound containing cobalt.

Vat dyestuffs of the anthraquinone, indigoid and thicindigoid series may be printed on cellulose fabrics by the process of the invention. All vat dyestufis suitable for printing by known flash-age techniques may be applied by the process of, the invention. Such dyes are indicated in the table on pages 316 and 341 of Textile Printing with Caledon Durindone and Soledon Dyes, published in 1961 by Imperial Chemical Industries Limited. In particular, very good results are obtained with the followmg Vat Yellow 13, CI. 65425 Vat Orange 15, CI. 69025 Vat Brown 3, CI. 69015 Vat Red 31, 2,5 bis(1-amino-2-anthraquinonyl)4,3,4-

oxidiazole Vat Red 1, CI. 73360 Vat Violet 2, CI. 73385 Vat Violet 1, CI. 60010 Vat Blue 6', CI. 69825 Vat Green 1, CI. 59830 Vat Green 26, reaction of 3-a-anthraquir1onyl aminobenzanthroneanthraquinoneacridine and aluminum chloride with M-nitrobenzene sulfonate and sodium chloride Vat Black 16, CI. 59855 The abbreviation C.I. refers to Colour Index (Second Edition) published jointly by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists.

The vat dyestuif dispersion may be thickened with any thickener, for example starch and modified starches, modified celluloses such as methyl and carboxymethyl cellulose, dextrin, locust bean gums or alginates. To obtain sharply defined prints it is preferred to use a thickener containing at least one constituent which coagulates on treatment with alkali, electrolyte or heat, for example a locust bean gum or an alginate. Suitable thickeners are described on pages 136 and 137 of Textile Printing With Caledon, Durindone and Soledon Dyes. Excellent results are obtained with the thickener described at the commencement of the examples.

As examples of alkalis which may be used in the process of the invention we mention the carbonates and hydroxides of sodium and potassium. It is Well known that certain vat dyestuffs require the presence of sodium or potassium hydroxide while others can be fixed with a milder alkali such as a carbonate.

The reduction catalyst used in the process of the invention may be an inorganic or organic acid salt of nickel, for example nickel sulphate, chloride or acetate or it may be an inorganic compound of cobalt such as cobalt hydroxide, carbonate, chloride or sulphate, or an organic acid salt, for example cobalt acetate or benzoate, or a coordination complex of cobalt with, for example, acetylacetone, 2,4 pentanedione, benzildioxime, dimethylglyoxirne, ethylene diamine or bis(salicylidine)ethylene diamine.

As specific examples of cobalt complexes which may be used in the process of the invention we mention the following:

[Co (Ni-l 2 a-benzildioxime) N0 CO (NI-I (N0 dimethylglyoxime) Na[Co (dirnethylglyoxime 2 (N0 [Co ethylenediamine) CI ICI [Co(ethylenediamine) N0 N0 The effectiveness of inorganic catalysts may be increased by admixture With a B-hydroxyanthraquinone especially Z-hydroxyanthraquinone, anthrafiavic acid, or isoanthrafiavic acid.

The cobalt complexes of anthraquinone ,B-hydroxy com pounds are very efficient reduction catalysts and in particular the cobalt complexes of anthraflavic acid, isoanthraflavic acid (2:7-dihydroxyanthraquinone) and 2- hydroxyanthraquinone are of especial value in the process of the invention since very small quantities of these catalysts are effective in increasing the rate of reaction between the vat dye and the reducing agent.

The cobalt complexes of anthraquinone ,G-hydroxycompounds are novel compounds and as such they are a fea* ture of the invention.

The cobalt complexes of fi-hydroxyanthraquinone compounds may be manufactured by adding, preferably at about 70 0, about 1.1 times the theoretical amount of cobalt sulphate to an aqueous solution prepared by dissolving the fl-hydroxyanthraquinone compound in water containing the theoretical amount of caustic alkali. The complex is precipitated and may be filtered off and washed free of soluble cobalt salts.

Water-soluble catalysts may be used as aqueous solutions and water-insoluble catalysts may be used in the form of dispersions. The amount of catalyst employed is 0.01% to of the weight of the print paste, 0.1% being adequate in most cases. Inorganic catalysts are in general less effective than organic compounds, especially the coordination complexes of cobalt and larger quantities of the inorganic catalysts are often required. Small quantities of inorganic catalysts may be made effective by adding about 0.005% to 1.0% of anthraquinone or a hydroxy derivative thereof, based on the weight of printing paste. Steaming times of to 40 seconds are usually adequate, but longer steaming has no adverse effect. 1

In one embodiment of the process of the invention the reduction catalyst is included in the printing paste and the fabric after application of the printing paste is padded with an alkaline solution of a reducing agent and steamed.

In a second embodiment of the process of the invention the printing paste contains a reducing agent and the fabric after application of the printing paste and drying is padded with an alkaline solution containing a reduction catalyst and steamed. If desired this process may be used to print vat dyestuffs on fabric previously dyed or padded with a dischargeable dyestulf so that a coloured discharge print is obtained on a coloured background. Dischargeable direct or reactive dyes may be used. When reactive dyes are used the alkaline padding liquor also serves to promote reaction between the dye and cellulose fibres.

In the process of the invention it is preferred to use sodium sulphoxylate'formaldehyde as reducing agent because of its cheapness and because, when it is used, the fabric after application of the printing paste may be stored for a considerable period (indefinitely when the first embodiment of the process is used). Even after padding there is no marked tendency for the reducing agent to become oxidised by exposure to the air. Moreover the padding liquor is stable even if it becomes heated, for example by proximity to the steaming equipment. Prints obtained using sodium sulphoxylate formaldehyde, in the process of the invention are at least equal in strength to prints obtained by use of sodium dithionite under similar conditions, but in absence of catalyst.

When the process of our invention is carried out using acetaldehyde sulphoxylate or sodium dithionite as reducing agent fixation of the vat dyestuff on the fabric takes place more quickly than is the case when no catalyst is employed. In consequence the process of the invention produces improved penetration and fixation by providing greater opportunity for the reduced dyestuff to diffuse into the fabric during the short steaming operation. The effect is especially noticeable when a heavy fabric is printed. The cobalt complexes of B-hydroxyanthraquinones such as Z-hydroxyanthraquinone, anthrafiavic acid and isoanthraflavic acid are particularly efiective in improving the 4 penetration and fixation obtained when acetaldehyde sulphoxylate or sodium dithionite is used as reducing agent.

After carrying out the process of the invention the prints may be finished in known manner, for example by rinsing in water, oxidising if necessary in a dilute solution of bichromate and finally soaping.

The invention is illustrated but not limited by the following examples in which the parts are by weight.

The thickening used in these examples is prepared as follows:

Part I.880 parts of carragheen moss is left to soak. for 16 hours in 12,000 parts of water. 388 parts of wheat starch is pasted with 4000 parts of water and added to the carragheen moss. The mixture is boiled for 15 minutes, cooled and diluted with water to.20,000 parts.

Part II.186 parts of methyl cellulose ether is added to 3750 parts of boiling water and the mixture is cooled and diluted to 4,000 parts.

Parts I and II are mixed.

In all the examples this thickening may be replaced by any of the other thickeners which are commonly used in textile printing. Good fixation of dyestuff is achieved with any thickeners, but sharply defined prints may not be obtained unless the thickener contains a constituent which coagulates with alkali, electrolyte or heat.

In Examples 1 to 8 an air passage of up to one minute may be given between padding and steaming without affecting the results described.

Example 1 A cotton fabric is printed with the following print paste:

1 100 parts of a 6% aqueous dispersion of Vat Red 31, i.e.,

After printing and drying liquor containing parts of sodium formaldehyde sulphoxylate (C.I. re-

ducing agent 2) 75 parts of aqueous sodium hydroxide solution (SG 1.34)

25 parts of anhydrous sodium carbonate 820 parts of water The fabric while still moist is exposed for 20 seconds to an air free steam atmosphere without excess pressure. To finish the print the fabric is treated for 2 minutes in cold running water, oxidised in a cold aqueous solution containing 1 part of sodium bichromate and 1 part of 40% acetic acid in 1000 parts of water, rinsed, soaped, again rinsed and dried.

A red print on a white background is obtained which is equal in strength to one produced under similar conditions, using 2. padding solution of sodium dithionite and sodium hydroxide.

In place of cotton fabric in this example, viscose, fabric may be used. A strong red print is obtained.

the fabric is padded with a Example 2 A cotton fabric is printed with the following print paste:

parts of a 20% aqueous dispersion of Vat Violet 2, Cl. 733385 10 parts of cobalt sulphate heptahydrate 290 parts of water 700 parts of thickening The fabric'while still moist is exposed for 40 seconds to an air free steam atmosphere without excess pressure. The print is then finished as in Example 1. A strong bluish red print on a white background is obtained which is equal in strength to one produced under similar conditions, using a padding solution of sodium dithionite and sodium hydroxide.

Example 3 A cotton fabric is printed with the following print paste:

30 parts of a 33% redispersible powder of Vat Green 26 which is the reaction product of 3-oa-anthraquinonyl amino-benzanthroneanthraquinoneacridine and aluminum chloride with M-nitrobenzene sulfonate and sodium chloride 2 parts of nickel sulphate, chloride, or acetate 268 parts of water 700 parts of thickening After printing and drying the print is padded with a liquor of the same composition as the padding liquor used in Example 1.

The fabric while still moist is exposed for 40 seconds to an air free steam atmosphere without excess pressure. The print is then finished as in Example 1. An olive green print on a white background is obtained which is equal in strength to one produced under similar conditions using a padding solution of sodium dithionite and sodium hydroxide.

Example 4 A cotton fabric is printed with the following print paste:

50 parts of a 12% aqueous dispersion of Vat Green 1,

1 part of cobalt sulphate heptahydrate 0.5 part of 2:o-dihydroxyanthraquinone 248.5 parts of Water 700 parts of thickening After printing and drying the print is padded with a liquor of the same composition as the padding liquor of Example 1.

The fabric is exposed while still moist for 20 seconds to air free steam atmosphere without excess pressure. The print is then finished as in Example 1.

A bright green print on a white background is obtained which is equal in strength to one produced under similar conditions, using a padding solution of sodium dithionite and sodium hydroxide.

Example 5 A catalyst dispersion is prepared as follows:

100 parts of a 25% dispersion of anthrafiavic acid in Water are diluted with 200 parts of water and heated to 60 C.

20 parts of aqueous sodium hydroxide solution (SG 1.34)

are then added. 58 parts of cobalt sulphate heptahydrate are then added in the form of a 1:2 aqueous solution. The resulting precipitate is filtered, washed with boiling water and filtered again.

The residue is then ball milled with 2.5 parts of a sulphonated naphthaleneformaldehyde condensate and sufficient water to make a total of 250 parts.

A cotton fabric is printed with the following print paste:

100 parts of a 12% aqueous dispersion of Vat Green 1,

40 parts of the catalyst dispersion obtained as described above 160 parts water 700 parts of thickening After printing and drying the print is padded with a d liquor of the same composition as the padding liquor used in Example 2.

The fabric is exposed while still moist for 20 seconds to an air free steam atmosphere Without pressure.

The print is then finished as in Example 2.

A bright green print on a white background is obtained which is at least as strong as one produced under similar conditions using a padding solution of sodium hydroxide and sodium dithionite and very much stronger than one produced under the conditions of this example but omitting the catalyst from the print paste.

Example 6 parts of ,8--hydroxyanthraquinone are stirred in 2000 parts of water at C. until thoroughly pasted. A solution of 10.7 parts of sodium hydroxide in parts of water is added, and to the dark red solution so obtained a solution of 41.2 parts of cobalt sulphate heptahydrate in parts of water is added. After about 30 seconds a buff coloured precipitate begins to form and stirring is continued for a further hour. The precipitate is filtered, washed with 5000 parts of water, and the damp filter cake is milled with Water and the sodium salt of a formaldehyde-naphthalene sulphonic acid condensate.

The dispersion so obtained is used in the printing of vat dyestuffs according to the recipe given in the latter part of Example 5.

Example 7 Example 5 is repeated, using isoanthrafiavic acid in place of anthrafiavic acid.

Example 8 A cotton fabric is printed with the following print paste:

100 parts of a 21% aqueous dispersion of Vat Red 19,

1 part of NR [Co(dimethylglyoxime) (N0 299 parts of water 600 parts of thickening After printing and drying the print is padded with a liquor of the same composition as the padding liquor used in Example 1.

The fabric while still moist is exposed for 40 seconds to an air free steam atmosphere without excess pressure. The print is then finished as in Example 1. A dull red print on a white background is obtained which is equal in strength to one produced under similar conditions but omitting the NH [Co(dimethylglyoxime) (NO from the printing paste and using a padding solution containing sodium dithionite and sodium hydroxide.

In place of NH [Co(dimethylglyoxime) NG in this example there may be used any of the previously mentioned complex organic compounds of cobalt.

Example 9 A cotton fabric is printed with the following print paste:

100 parts of an 18% aqueous dispersion of Vat Blue 4,

5 parts of the catalyst dispersion (containing 12% effective agent) obtained as described in Example 5 parts of water 700 parts of thickening After printing and drying the print is padded with a liquor of the following composition:

100 parts of acetaldehyde sulphoxylate (50%) (Cl. Re-

ducing Agent 13) 120 parts of aqueous sodium hydroxide solution (SG.

200 parts of gum tragacanth (10%) solution 580 parts water The fabric while still moist is exposed for 40 seconds to an air free steam atmosphere without excess pressure. To complete the process the fabric is treated for 2 minutes in cold running water, oxidised in a cold aqueous solution containing 1 part of sodium bichromate and 1 part of 40% acetic acid in 1000 parts of water, rinsed, soaped, again rinsed and dried.

A blue print on a white background is obtained which is noticeably brighter and stronger than one produced when the process of this example is repeated, omitting the catalyst from the print paste.

Example 10 In place of 100 parts of the dyestutf used in Example 7, there are used (a) 100 parts of a 15% aqueous dispersion comprising a mixture of equal parts of Vat Orange 5, 01. 73335 and Vat Red 1, CI. 73360 -(b) 150 parts of a 10% aqueous dispersion of Vat Brown 3, Cl. 69015, or

100 parts of a 14% dispersion of Vat Orange 3, CI.

The prints obtained are stronger than the corresponding prints produced when the catalyst is omitted from the print paste.

Example 11 A linen fabric weighing 9 ounces per square yard is printed with the following print paste:

The fabric while still moistis exposed for 20 seconds to an air free steam atmosphere without excess pressure. To complete the process the fabric is treated for 2 minutes in cold running water, oxidised in a cold aqueous solution containing 1 part of sodium bichromate and 1 part of acetic acid in 1000 parts of water, rinsed, soaped, again rinsed and dried.

A red print on a white background is obtained which is stronger than one produced when the process of this example is repeated, omitting the catalyst from the printing paste.

We claim:

1. Process for the fixation of vat dyestuffs on cellulose fabrics which comprises steaming for less than 2 minutes a cellulose fabric having applied thereto a thickened vat dyestufi dispersion, an alkali, a reducing agent for the vat dyestufi and, as reduction catalyst, a complex of cobalt with a ,B-hydrcxyanthraquinone.

2. Process according to claim 1 wherein the reduction catalyst is the cobalt complex of Z-hydroxyanthraquinone.

3. Process according to claim 1 wherein the reduction catalyst is the cobalt complex of anthraflavic acid.

4. Process according to claim 1 wherein the reduction catalyst is the cobalt complex of isoantraflavic acid.

5. Process for the fixation of vat dyestuffs on cellulose fabrics which comprises steaming for less than two minutes a cellulose fabric having applied thereto a thickened vat dyestuff dispersion, an alkali, sodium sulphoxylate formaldehyde and, as reduction catalyst, a complex of cobalt with a ,B-hydroxyanthraquinone.

6. Process according to claim 5 wherein the reduction catalyst is the cobalt complex of Z-hydroxyanthraquinone.

7. Process according to claim 5 wherein the reduction catalyst is the cobalt complex of anthraflavic acid. I

8. Process according to claim 5 wherein the reduction catalyst is the cobalt complex of .isoanthrafiavic acid.

References Cited by the Examiner UNITED STATES PATENTS NORMAN G. TORCHIN, Primary Examiner. 

1. PROCESS FOR THE FIXATION OF VAT DYESTUFFS ON CELLULOSE FABRICS WHICH COMPRISES STEAMING FOR LESS THAN 2 MINUTES A CELLULOSE FABRIC HAVING APPLIED THERETO A THICKENED VAT DYESTUFF DISPERSION, AN ALKALI, A REDUCING AGENT FOR THE VAT DYESTUFF AND, AS REDUCTION CATALYST, A COMPLEX OF COBALT WITH A B-HYDROXYANTHRAQUINONE. 